Fenugreek (Trigonella foenum-graecum) has attracted considerable interest as a natural source of soluble dietary fiber and diosgenin (sapogenins). The fenugreek seed contains a central hard, yellow embryo surrounded by a corneous and comparatively large layer of white, semi-transparent endosperm. This endosperm contains galactomannan gum. The endosperm is surrounded by a tenacious, dark brown husk. The color of the gum fraction depends upon the amount of outer husk (brown color) and cotyledon (yellow color) present.
There are commercial uses for the various fractions of the fenugreek seed. The commercial fenugreek oleoresins are used as an ingredient for imitation maple flavors and is effective in butter, butterscotch, black walnut, nut and spice flavors. Another fraction of the fenaugreek seed has been found to be a quantity of saponins. Fenugreek seed saponins are steriodal in nature with diosgenin as the main sapogenin. Disogenin is used by the drug industry as a precursor to progesterone (steriod hormones) which is used in the manufacturing of oral contraceptives.
Currently, the pharmaceutical industry use either synthetic or natural diosgenin for progesterone production. Some manufacturers are very apprehensive in switching to natural product because of supply and impurity problems associated with the natural product and as such the reliable production of natural diosgenin would have significant market potential.
Saponins have many flavoring, sweetening, antioxidant, foaming, complexing, sequestration, anticarcinogenic and antimicrobial properties. They could be used as an antioxidant, emulsifier, surfactant, ingredient for nutraceutical in food, drug, health food and cosmetic industry and as such represent another value-added fraction for recovery. Until recently, saponins have been largely overlooked except in cases where their presence was considered toxic. There are human benefits to the use of galactomannans as well. In particular, it has been reported that fenugreek galactomannan is most evident in the lowering of cholesterol in both liver and blood plasma..sup.1 FNT .sup.1 A. J. Evans et al., "Relationship Between Structure and Function of Dietary Fiber: A Comparative Study of the Effects of Three Galactomannans on Cholesterol", (1992) British J. Nut, 68(1):217-229.